A complete potential profile will be obtained on salamander skins in vivo. Na and C1 transport will be varied by changing external concentrations and adding amiloride. Effects of single ion substitutions (Na or C1 separately) on the PD will be determined. Isolation of outer membrane fragments will be developed. If these fragments form functional vesicles, Na transfer will be measured and its parameters compared with those estimated from the behavior of intact epithelia (salamander skin). BIBLIOGRAPHIC REFERENCES: Greenwald, L. and Kirschner, L. B.: The Effect of Poly-l-lysine, Amiloride and Methyl-l-lysine on Gill Ion Transport and Permeability in the Rainbow Trout. J. Memb. Biol. 1976, in press. Baldwin, G. F. and Kirschner, L. B.: Sodium and Chloride Regulation in Uca Adapted to 176 percent Sea Water. Physiol. Zool. 1976, in press.